Link State Routing K. Talaulikar
Internet-Draft P. Psenak
Intended status: Standards Track Cisco Systems
Expires: January 5, 2020 July 4, 2019
Advertising L2 Bundle Member Link Attributes in OSPFdraft-ketant-lsr-ospf-l2bundles-00
Abstract
There are deployments where the Layer 3 interface on which OSPF
operates is a Layer 2 interface bundle. Existing OSPF advertisements
only support advertising link attributes of the Layer 3 interface.
If entities external to OSPF wish to control traffic flows on the
individual physical links which comprise the Layer 2 interface bundle
link attribute information about the bundle members is required.
This document introduces the ability for OSPF to advertise the link
attributes of layer 2 (L2) Bundle members.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 5, 2020.
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Internet-Draft OSPF L2 Bundles July 2019
adjacency segment identifier (Adj-SID) link attribute for OSPFv2 and
OSPFv3 respectively which can be used as an instruction to forwarding
to send traffic over a specific link [RFC8402]. This document
enables the advertisement of the Adj-SIDs using the same Adjacency
SID sub-TLV at the granularity level of each L2 Bundle member link so
that traffic may be steered over that specific member link.
Note that the new advertisements at the L2 Bundle member link level
in this document are intended to be provided to external (to OSPF)
entities and does not alter or change OSPF route computation process.
The following items are intentionally not defined and/or are outside
the scope of this document:
o What link attributes will be advertised. This is determined by
the needs of the external entities.
o A minimum or default set of link attributes.
o How these attributes are configured
o How the advertisements are used
o What impact the use of these advertisements may have on traffic
flow in the network
o How the advertisements are passed to external entities
2. L2 Bundle Member Attributes
A new L2 Bundle Member Attributes sub-TLV is introduced to advertise
L2 Bundle member attributes in both OSPFv2 and OSPFv3. In case of
OSPFv2, this sub-TLV is an optional sub-TLV of the OSPFv2 Extended
Link TLV that is used to describe link attributes via the OSPFv2
Extended Link Opaque LSA [RFC7684]. In case of OSPFv3, this sub-TLV
is an optional sub-TLV of the Router Link TLV of the OSPFv3 E-Router-
LSA [RFC8362].
When the OSPF adjacency is associated with L2 Bundle interface, this
sub-TLV is used to advertise the underlying L2 Bundle member links
along with their individual link attributes. Inclusion of this
information implies that the identified link is a member of the L2
bundle associated with OSPF L3 link and that the member link is
operationally up. Therefore advertisements of member links MUST NOT
be done when the member link becomes operationally down or it is no
longer a member of the identified L2 Bundle.
The L2 Bundle Member Attributes sub-TLV has the following format:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L2 Bundle Member Descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Member Link attribute sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: L2 Bundle Member Attributes sub-TLV Format
Where:
Type: TBD1 for OSPFv2 and TBD2 for OSPFv3
Length: Variable.
L2 Bundle Member Descriptor: A 4 octet Link Local Identifier as
described in [RFC4202] and used in [RFC8510] for the member link.
Link attributes for L2 Bundle Member Links are advertised as sub-TLVs
of the L2 Bundle Member Attribute sub-TLV.
In the case of OSPFv2, the L2 Bundle Member Attributes sub-TLV shares
the sub-TLV space of the Extended Link TLV and the sub-TLVs of the
Extended Link TLV MAY be used to describe the attributes of the
member link. The Figure 2 below lists sub-TLVs and their
applicability for L2 Bundle member links. The sub-TLVs that are not
applicable MUST NOT be used as sub-TLVs for the L2 Bundle Member
Attributes sub-TLV. Specifications that introduce new sub-TLVs of
the Extended Link TLV MUST indicate their applicability for the L2
Bundle Member Attributes sub-TLV. An implementation MUST ignore any
sub-TLVs received that are not applicable in the context of the L2
Bundle Member Attribute sub-TLV.
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